RRB NTPC CBT-1 previous year question
A cistern is filled by two taps, C and D, in 54 minutes and 81 minutes, respectively. There is also a drain E at the bottom. If all three are opened simultaneously, the cistern is filled in 108 minutes. In how many minutes can drain E alone empty the cistern? (up to two decimal places)
Asked in RRB NTPC 2026 — 16 June Shift 3 · Quantitative Aptitude
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Correct answer: (C) 46.29
Combined rate with drain: 1/54+1/81-1/E=1/108. Solving gives 1/E=1/54+1/81-1/108≈0.02161, so E≈46.29 minutes.
हिंदी में प्रश्न
एक टंकी दो नलों - 54 और 81 के माध्यम से क्रमश: 54 मिनट और 84 मिनट में भर जाती है। टंकी के तल. में एक निकास नल 108 भी Sl यदि तीनों नलों को एक साथ खोला जाता है, तो टंकी 408 मिनट में भर जाती है। निकास नल & अकेले cpl को कितने मिनट में (दशमलव के दो स्थानों तक पूर्णांकित) खाली कर सकता है?
उत्तर जाँचने के लिए किसी विकल्प पर टैप करें।
उत्तर और व्याख्या देखें
सही उत्तर: (C) 46.29
नाली सहित संयुक्त दर: 1/54+1/81-1/E=1/108। हल करने पर 1/E=1/54+1/81-1/108≈0.02161, अतः E≈46.29 मिनट है।
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